Effect of acute changes in glomerular filtration rate on Na+/H+ exchange in rat renal cortex.
Effect of acute changes in glomerular filtration rate on Na+/H+ exchange in rat renal cortex.
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肾小球滤过率急性变化对大鼠肾皮质 Na /H 交换的影响。
DOI：
10.1172/jci115715
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Gennari,FJ
中科院分区：
文献类型：
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作者：
Maddox,DA;Fortin,SM;Tartini,A;Barnes,WD;Gennari,FJ
在Munich-Wistar大鼠中进行了研究，以评估GFR变化诱导的滤过性碳酸氢盐（FLHCO 3）变化对肾刷状缘膜囊泡（BBMV）中Na+/H+交换活性的影响。在研究的每只动物中，将GFR、FLHCO 3、全肾和近端小管HCO 3重吸收（APRHCO 3）的全肾和微穿刺测量与H+梯度驱动的22 Na+摄取的BBMV测量相结合。在三个Na+浓度梯度下测量22 Na+摄取，以允许计算Na+/H+交换的Vmax和Km。通过研究在水肿、血浆充盈和急性血浆扩张条件下的动物，GFR各不相同。血浆给药诱导的GFR、FLHCO 3和APRHCO 3增加与BBMV中Na+/H+交换的Vmax增加直接相关。钠的Km不受影响。在血浆扩张大鼠中，Na+/H+交换的Vmax比缺水大鼠高22%（P <0.025），而APRHCO 3高86%（P <0.001）。这些结果表明，增加FLHCO 3，诱导急性GFR增加，刺激近端肾小管上皮细胞的Na+/H+交换活性。这种刺激是一种机制，可以部分解释近端碳酸氢盐重吸收的递送依赖性。
Studies were undertaken in Munich-Wistar rats to assess the influence of changes in filtered bicarbonate (FLHCO3), induced by changes in GFR, on Na+/H+ exchange activity in renal brush border membrane vesicles (BBMV). Whole-kidney and micropuncture measurements of GFR, FLHCO3, and whole-kidney and proximal tubule HCO3 reabsorption (APRHCO3) were coupled with BBMV measurements of H+ gradient-driven 22Na+ uptake in each animal studied. 22Na+ uptake was measured at three Na+ concentration gradients to allow calculation of Vmax and Km for Na+/H+ exchange. GFR was varied by studying animals under conditions of hydropenia, plasma repletion, and acute plasma expansion. The increase in GFR, FLHCO3, and APRHCO3 induced by plasma administration correlated directly with an increase in the Vmax for Na+/H+ exchange in BBMV. The Km for sodium was unaffected. In the plasma-expanded rats, the Vmax for Na+/H+ exchange was 22% greater than in the hydropenic rats (P less than 0.025) whereas APRHCO3 was 86% greater (P less than 0.001). These results indicate that increases in FLHCO3, induced by acute increases in GFR, stimulate Na+/H+ exchange activity in proximal tubular epithelium. This stimulation is a mechanism which can, in part, account for the delivery dependence of proximal bicarbonate reabsorption.